Spark plug having a variable spark gap and a non-baffling electrode



July 29, 1958 REGAR 2,845,566

SPARK PLUG HAVING A VARIABLE SPARK GAP AND A NON-BAFFLING ELECTRODE Filed Jan. 22, 1957 FLG.2. FlG.5.

1N VENTOR HAROLD D. REGAR.

ATTORNEY United States Patent SPARK PLUG HAVING A VARIABLE SPARK GAP AND A NON-BAFFLING ELECTRODE Harold D. Regar, Temple, Pa.

Application January 22, 1957, Serial No. 635,392

' 1 Claim. or. 313-141 This invention relates to an improved spark plug and particularly to a spark plug having not only a variable spark gap but also a non-bathing electrode.

A further object of this invention is to provide a spark plug wherein the spark gap provided extends from a desired minimum to a desired maximum so that it provides a proper spark gap for all types of running, both at idling speed and at high speed, and furthermore provides a suitable spark gap when the minimum gap tends to enlarge due to corrosion of the electrodes, and it takes quite some time before the maximum spark gap is exceeded whereby the spark plug will remain in satisfactory operation for a much longer period of time.

Yet a further object of this invention is to provide a spark plug wherein the electrode from the spark plug shell provides a minimum amount of resistance or bafiling to the gases going to and from the spark gap so that the gases may reach the spark gap more readily and when exploded may depart therefrom more readily, thereby minimizing the heat absorption and minimizing the heat reflection from the shell electrode to the central electrode.

A further object of this invention is to provide a spark plug that will operate much more efiiciently and for a much greater period than a conventional spark plug, yet

differs principally therefrom in the construction and arrangement of the shell or negative electrode and its relationship to the coaxial or positive electrode.

Still a further object of this invention is to provide a spark plug wherein the shell or negative electrode is ribbon shaped, extending downwardly from the shell and then inwardly, but twisted so that the plane of the ribbon surfaces extend parallel to the axis of the shell and of the coaxial or positive electrode, and wherein the ribbon edge that extends close to the positive or coaxial electrode is set at such a tapering angle thereto that it provides a spark gap varying in distance from the minimum desirable spark gap to the maximum desirable spark gap, thereby providing a long-lived spark plug with a minimum of heat reflection from the ribbon electrode to the interior of the spark plug as well as a minimum of heat absorption, and likewise .a minimum of interference with the passage of the gases to and from the spark gap and the interior of the spark plug thereby providing a cooler burning spark plug.

Still a further object of this invention is to provide a ribbon-shaped spark plug electrode having its termination nose edge within the projection of the coaxial spark plug electrode, and wherein the thickness of the ribbon electrode is less than the thickness or diameter of the coaxial spark plug electrode.

Still a further object of this invention is to provide a spark plug having a ribbon-shaped electrode providing the shell or negative electrode and wherein this shell electrode has a minimum almost knife edge surface in the direction of the entry and exit of gases to the spark gap and the interior of the spark plug yet at the same time due to the width of the ribbon has a substantial amount of body so as to be able to undergo 2,845,566 Patented July 29, 1958 seriously affecting the operation of the spark plug, particularly due to the fact that such erosion at most merely increases the minimum gap of the spark plug without increasing the maximum gap of the spark plug for a considerable period of time, due to the variable spark gap provided by this invention.

Still a further object of this invention is to provide a spark plug having a ribbon-shaped electrode which provides not only a minimum amount of bathing to the gases entering and leaving the spark plug interior and the spark gap, but also provides a minimum obstruction to permit sand blasting for cleaning and removing carbon and lint deposits therefrom in a more thorough manner, providing for extreme free breathing, free burning and cooler burning, and operating under closer gapping thus prolonging the life of the electrode.

With the foregoing and other objects in view, this invention comprises the combination, construction and arrangement of parts hereinafter set forth, claimed and disclosed in the accompanying drawing, wherein:

Fig. l is an elevational view of a spark plug to which this invention has been applied.

Fig. 2 is an enlarged fragmentary view of the spark end of the spark plug.

Fig. 3 is a view similar to and at right angles to Fig. 2.

Fig. 4is a bottom plan view of Figs. 2 and 3.

There is shown the spark plug of this invention at 10 having the usual threaded shell 12 and wrench cooperating hex 14 in which is secured by the conventional nut 16 the coaxial insulator 18 through which extends a coaxial electrode 20 which terminates, at the threaded end of the shell 12 in a sparking end surface 22. As shown, the electrode 20 is generally cylindrical in shape, at least at its sparking end adjacent the sparking end surface 22, thereby of course causing the sparking end surface 22 to be circular in outline, although, it may be of any other shape within the scope of what is hereinafter claimed. This electrode 20 which is coaxial with the insulator 18 and the threaded shell 12 generally operates as a positive electrode.

The negative elect-rode constituting substantially the essence of this invention, is shown at 24 as being ribbon shaped and depending from the shell 12 downwardly therefrom in a plane substantially parallel to a tangent to the circular shell 12 a slight distance, and then is twisted or bent at an angle substantially degrees as shown at 26 so as to bring the plane of the ribbon surfaces 28 of the electrode 24 into coincidence or parallel to the axis of the coaxial spark plug electrode 20.

The ribbon edge 30 of ribbon electrode 24 extends downwardly at a slight angle and inwardly from the shell toward the electrode 20 and terminates in a sharp nose end 32 formed by the acute angle between the ribbon edge 30 and the end edge 34, this acute angle being preferably substantially 45 degrees, thus causing the other end of the end edge 34 to form an obtuse angle with the other ribbon edge 36 of electrode 24. Furthermoreit will be noted as particularly shown in Fig. 4, that the sharp nose end 32 lies within a projection of the end sparking surface 22 of the coaxial electrode 20.

This sharp nose end 22 will preferably be located at a distance of .035 inch from the sparking end surface 22 of electrode 20, and due to the slight angle of the ribbon end 30, this gap between the ribbon edge 30 and the sparking end surface 22 of coaxial electrode 20 decreases to a minimum of .025 inch at the nearest point between the ribbon edge 30 and the sparking end surface 22, thus providing a spark gap between the electrodes varying between this minimum and maximum distance, the sharp single nose end 22 thus being located at the maximum 3. distance of the spark gap within the projection of the end sparking surface of the coaxial electrode 20.

In operation, when high voltage passes across the tapered gap, it not only sparks to its nearest point of .025 inch, but flares across to the wider space of .035 inch, and all spacing between these two points to make a spark adaptable to any and all gap settings of the straight line settings and so forth. When erosion takes place, as it inevitably does over a long period of time, while the minimum distance of the spark gap may increase slightly, it takes a very long time for this minimum distance to erode to beyond the maximum desirable distance so that the spark plug remains in use much longer than otherwise possible. Due to the thin ribbon edges extending in the direction of the flow of gases into and out of the spark plug, there is a minimum amount of baffle or obstruction to the flow of the gases in both directions, and likewise there is a minimum amount of heat absorption from the gases as well as a minimum amount of reflection of heat from the ribbon edge to the other electrode, thus providing a much cooler burning spark plug.

Although this invention has been described in considerable details, such description is intended as being illustrative rather than limiting, since the invention may be variously embodied, and the scope of the invention is to be determined as claimed.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

A spark plug comprising a shell, an insulator coaxial of and within said shell, a cylindrical electrode coaxial of and extending through said insulator and terminating in a circular sparking end surface, and a fiat, ribbonshaped electrode extending from said shell with the plane of its ribbon surfaces parallel to a tangent to said shell downwardly and inwardly twisted at an angle of slightly less than ninety degrees therefrom with the plane of its ribbon surfaces coinciding with the axis of said coaxial electrode, one ribbon edge of said ribbon electrode extending at a slight angle to and adjacent to and partly across said sparking end surface of said coaxial electrode, said ribbon edge providing a spark gap between said ribbon edge and said sparking end surface, said gap varying from a minimum of .025 inch to a maximum of .035 inch, the thickness of said ribbon electrode between its ribbon surfaces being less than the diameter of said coaxial electrode sparking end surface, said ribbon edge terminating in a sharp nose end lying within the axial projection of said coaxial electrode, said sharp nose end being provided by the end edge of said ribbon electrode extending at an acute angle between said sparking ribbon edge and at an obtuse angle to said other ribbon edge, said ribbon edges and angle end edge minimizing baffling of gas flow to and from the spark gap and also minimizing heat reflection to said coaxial electrode, insulator and shell.

References Cited in the file of this patent UNITED STATES PATENTS 1,538,870 Champion May 1"), 1925' 1,568,621 Rabezzana Jan. 5, 1926 2,207,175 Kral July 7, 1940 2,518,844 Wetzel Aug. 15, 1950 2,795,723 Townsend June 11, 1957 

